The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In Friction Stir Welding (FSW) applications there are two primary types of FSW tools. One of the most common types of FSW tools is a fixed pin type tool. The FSW pin tool is intimately connected to the FSW shoulder tool, and the two effectively act as a single unit. The single shoulder/pin is the most common of the welding tools.
The second type of FSW tool is a Retractable Pin Tool (RPT), with two individual tools identified as the pin and shoulder tools. The shoulder tool is a hollow shank with a flat, convex, or concave surface. The shoulder tool has a centered tight tolerance hole (i.e., bore) that is formed through the shank, which allows the pin to pass through the hole in order to obtain required differences in pin length, for such applications as tapered skin welding. The shoulder generally is parallel with the surface when it makes contact, and the pin tool is perpendicular to the work surface. In the case of an RPT, there are two separate pieces that are independent, with clearance between pin and shoulder components.
When performing a FSW procedure, plasticized material migrates up the pin on both the fixed pin and retractable pin tool surfaces. When the weld path is complete, and the spindle stopped, the material that has migrated between the two tools cools and solidifies, essentially fusing the shoulder tool and the retractable pin tool together. The additional material in between the retractable pin tool and the shoulder tool is difficult to separate because the two tools are powered by separate spindle motors. If the motors start at a different speed the high torque created by the two different motors can easily break an expensive pin tool.
When manually trying to force the fixed pin tool from its shoulder tool, or the retractable pin tool from its shoulder tool, using hand tools, it is extremely easy to accidentally break the pin tool. The pin tool typically runs several hundred dollars in cost, and thus breakage of pin tools can amount to a significant expense. Breakage also can interfere with continuing operation of a FSR system, and thus negatively affect its overall productivity.